1. Field
The following description relates to a wireless power transmitter.
2. Description of Related Art
Currently, in the field of smart watches technological development trends include applications of low power Bluetooth™ communications, low power displays, low power mobile processors, batteries having improved levels of performance, and the like, in terms of hardware, as well as the simultaneous development of power management software capable of minimizing power consumption.
However, since battery capacity may be insufficient due to limited internal space in smart watches, frequent charging of smart watches is a significant restriction on extending related markets. To secure waterproof and dustproof performance in smart watches, it is believed that the introduction of a wireless charging solution capable of allowing for the removal of a universal serial bus (USB) connector from charging, as opposed to an existing wired charging scheme using a USB connector, will be very effective in broadening the market for such devices.
Although many smart watch development companies are currently attempting to employ wireless charging technology, commercialization of wireless charging technology is somewhat insufficient due to a mechanical appearance of smart watches which may be caused by the wireless charging technology, a small degree charging freedom, and low charging efficiency. It is also difficult to mount a reception (Rx) coil and a related circuit in a small internal space of a smart watch.
FIGS. 1A and 1B illustrate a wireless power transmitter disclosed in Korean Patent Laid-Open Publication No. 2012-0078995. As shown in FIGS. 1A and 1B, a transmission resonator may include one transmission conductive wire loop C and provide a horizontal magnetic field to the ground surface in a horizontal direction and a vertical magnetic field to the ground surface in a vertical direction using current I flowing through the transmission conductive wire loop C (see B1). In the vertical magnetic field, an electronic device, such as a cellular phone, having a substantially flat charging surface may be charged. In the horizontal magnetic field, an electronic device, such as a Virtual Reality Headset, having a curved charging surface may be charged.
In more detail, in the case of a direction of the current I as shown in FIG. 1A, a reverse direction magnetic field may be generated from the outside of the transmission conductive wire loop C to the inside thereof in a zone Z2, other than a zone Z1 between both ends E1 and E2 of the transmission conductive wire loop C.
Meanwhile, in case of a direction of the current I as shown in FIG. 1B, a reverse direction magnetic field may be generated from the outside of the transmission conductive wire loop C to the inside thereof and a reverse direction magnetic field may be generated from an upper portion of the transmission conductive wire loop C to a lower portion thereof in the zone Z1 between both ends E1 and E2 of the transmission conductive wire loop C.
Such reverse direction magnetic fields may cause problematic malfunctioning of an electronic circuit disposed in an electronic device.